Automatic Top / Middle / Bottom Alignment for 3D Text Object
You are right, aligning the overall text from top/bottom isn't available.

The Left/Right/Centre alter the location of the text relative to each line and allows adjusting the alignment of the text relative to other lines of text.

The up/down alignment only alters the text position relative to the object centre; this can be altered after text entry by moving the text object. Aligning each line left/right can only be done this way if you do one line per text object.

If you think up/down alignment is important, you should suggest it to one of the developers. I doubt this would be considered priority so unless a developer is interested in this you may have more luck in creating a patch yourself and submitting it for review.

Maybe an add-on could be created to add an option for top/middle/bottom alignment.